Acoustic properties of comfort sounds of 3-month-old Cameroonian (Nso) and German infants

Abstract

Little is known about the influence of cultural factors on early vocal development. This study aims to investigate comfort sounds of infants reared in very different cultural environments, namely Cameroonian Nso and German. These cultures differ not only with respect to their languages, but also with respect to the amount of language used in early interactional situations with infants as well as the caregivers’ contingent responsiveness to infant communicative signals. Participants were 14 German and 19 Nso healthy 3-month-old infants. About 800 comfort sounds were objectively analyzed with respect to melodic and spectral properties. No significant differences were found for mean F0, FM-amplitude, melody structure, and produced sound categories. Significant minor difference was found for mean sound duration. The results suggest a high similarity of the observed sound features between both groups and point to relatively universal developmental processes and a comparable state of vocal development at 3 months of age. However, signs of specific acoustic qualities in Nso infant vocalization were found that could indicate an early influence of cultural factors. Further studies are necessary to test this hypothesis.

Keywords:

• Melody
• Comfort sounds
• Vocal development
• Cross-cultural differences
• Mother–infant interaction

Acknowledgment

We thank Christian Naumann, Humboldt University of Berlin, for assistance in the interpretation of Nso infants’ click sounds. Peter Wermke, IT-Center of the University Wuerzburg, we thank for his support in data analysis.